围压对高温后玄武岩纤维混凝土渗透率及孔隙结构的影响

Effect of Confining Pressure on Permeability and Pore Structure of Basalt Fiber Reinforced Concrete after High Temperature

玄武岩纤维混凝土(BFRC)渗透性能对火灾后构件耐久性评估至关重要,开展了高温后BFRC变围压作用下渗透率测试以及孔隙结构变化特征研究,采用围压敏感系数和无因次渗透率分析了变围压过程中BFRC渗透率的演化规律.结果表明:围压加载过程中,BFRC渗透率呈负指数函数衰减,高温后试件初始渗透率随温度升高呈增大趋势,与基准混凝土(RC)相比,在100、300、600℃高温后BFRC的初始渗透率降低了48.16%、33.89%、1.57%;根据围压敏感系数将围压加载过程分为敏感区、过渡区和不敏感区,敏感区内BFRC的渗透率随围压增加降低幅度最大;围压作用后BFRC的孔隙结构向小尺寸孔隙发展,孔隙数量减少,致使其渗透率降低.

The permeability of basalt fiber reinforced concrete(BFRC)is critical to the durability assessment of members after fire.The permeability test and pore structure change characteristics of BFRC under variable confining pressure after high temperature were studied.The evolution of permeability was analyzed as well under the same conditions by using confining pressure sensitivity parameters and dimensionless permeability.Results show that during confining pressure loading,BFRC permeability attenuates as a negative exponential function,and the initial permeability increases with increasing temperature after high temperature.Compared with reference concrete(RC),the initial permeability of BFRC decreases by 48.16%,33.89%and 1.57%after 100,300 and 600℃.According to confining pressure sensitivity parameters,the loading process of confining pressure is divided into sensitive zone,transition zone and insensitive zone,and the permeability of BFRC in sensitive zone decreases most with the increases of confining pressure.After confining pressure,pore structure of BFRC develops to small-size pores and the number of pore decreases,resulting in lower permeability.